1. Technical Field
The subject disclosure relates to minimally invasive surgical procedures and apparatus and, more particularly, to instruments and methods for performing heart valve replacement surgery.
2. Background
The diagnosis and treatment of coronary disease and related conditions often requires repair or replacement of the valves located within the heart. Various factors, such as, for example, calcification, may result in the mitral or aortic valves becoming impaired or functionally inoperative requiring replacement. Where replacement of a heart valve is indicated, in general, the dysfunctional valve is cut out and replaced with either an artificial, synthetic heart valve or a harvested porcine heart valve. The replacement valve is typically sutured in place of the original valve.
More specifically, access to the heart in a patient's thoracic cavity is achieved by making a longitudinal incision in the chest. This procedure, referred to as a median sternotomy includes cutting through the sternum and forcing the two opposing halves of the rib cage to be spread apart allowing access to the thoracic cavity and thus the heart.
Suitable instruments for spreading and holding apart the rib cage are marketed by United States Surgical Corporation, Norwalk, Conn. These instruments include, for example, Mini-CABG* retractors and relted accessories. The Mini-CABG* universal base retractor includes a substantially planar base having an opening which can be positioned on the patient such that the opening overlies the incision at the operative site. Mini-CABG* retractors are slidably mounted on the base and are provided to spread apart the rib cage halves and engage and retract obstructing tissue. Surgical instruments that can be used to stabilize or manipulate the heart during surgery can also be secured to the base.
Once access to the thoracic cavity has been achieved, surgery on the heart to effect valve replacement may be performed. During some procedures, the heart beat is arrested by infusion of a cardioplegic fluid, such as potassium chloride (KCl), to paralyze the myocardium while blood flow circulation is maintained through known heart bypass techniques. Alternatively, the heart is allowed to beat to maintain circulation, while a localized area of the heart on which surgery is to be performed, is locally immobilized by various instruments.
The heart is incised and the defective valve is cut away leaving a surrounding area of locally tougher tissue. Known heart valve replacement techniques typically include individually passing sutures through the tough tissue to form an array of sutures. Free ends of the sutures are extended out of the thoracic cavity and laid, spaced apart, on the patient's body. The free ends of the sutures are then individually threaded through an edge around the circumference of the replacement valve or a supporting cuff. Once all sutures have been run through the valve, all the sutures are pulled up taught and the valve is slid or "parachuted" down into place adjacent the tough tissue. Thereafter, the replacement valve is secured in place using the sutures.
Where replacement is performed utilizing an artificial valve, hand held instruments in the form of a stick can be affixed to the valve and used to manipulate the replacement valve into place. The commercially available replacement valves are typically provided with a detachable holder structure which can be engaged by the hand tools.
While the above described procedures are sufficient to successfully position a heart valve within the heart, they are particularly time consuming. A more stable platform would be desirable for maintaining the valve in a fixed position to allow it to by secured in place. Therefore, a need exists for apparatus and procedures of quickly and efficiently positioning and affixing artificial heart valves within the heart.